PONE-D-19-35638

Degree day models to forecast the seasonal phenology of Drosophila suzukii (Diptera: Drosophilidae) in Midwest climate

PLOS ONE

Dear Dr. Guédot,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Your manuscript has been reviewed by three independent and qualified reviewers. They returned with contrasting recommendations (minor, major revisions and reject). Some comments are apparently serious, e.g., trap position, unconsidered factors (variety, pesticide applications, etc). Therefore, I need to read a full point by point rebuttal letter to the comments below, before taking any further editorial decision.

Specific comments from the academic editor:

- I suggest adding the crop system in the title. Moreover, although Midwest is pretty known I suggest adding US. (Diptera: Drosophilidae) could be deleted.

- the raw data file gives errors in most cells with formulae

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Additional Editor Comments (if provided):

Your manuscript has been reviewed by three independent and qualified reviewers. They returned with contrasting recommendations (minor, major revisions and reject). Some comments are apparently serious, e.g., trap position, unconsidered factors (variety, pesticide applications, etc). Therefore, I need to read a full point by point rebuttal letter to the comments below, before taking any further editorial decision.

Specific comments from the academic editor:

- I suggest adding the crop system in the title

- the raw data file gives errors in most cells with formulae

- please check for any reviewers' attachment

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

Reviewer #3: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: Yes

Reviewer #3: No

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript “Degree day models to forecast the seasonal phenology of Drosophila suzukii (Diptera: Drosophilidae) in Midwest climate” analyzes two predictive models (GLMM and GAMM) on the dynamic seasonal phenology of spotted-wing drosophila (SWD) based on four years of data. Furthermore, the authors of the manuscript have a useful amount of data about the SWD captures through the season to consider the fly abundance during the season. However, the manuscript is a bit confusing, and it is hard, at least for this reviewer, to follow the hypotheses, methodology and results obtained. In this sense, the manuscript would improve if it had a more precise distribution and data analyzed. Otherwise, it is complicated to evaluate the findings. My comments below try to explain the significant part of the shortcuts that I found during the reading.

Introduction:

The introduction needs more information about why the authors used two Generalized different models for the predictions.

Methods:

This section needs more detail about field information (maybe a figure, should help to do some visual idea about the field distribution).

There are 13 different locations with the cherry variety ‘Montmorency’; however, there one location (authors didn’t said which site is) with two different cherry varieties ‘Montmorency’ and ‘Balaton’. For this reason, this location should be excluded from the predictive models. The populations' capture in this field could increase or decrease (attract/repel SWD) in correlation with variety absent in another experimental field.

The abiotic conditions are essential if this study is focused on predictive models that consider temperature and relative humidity as a key factors. However, the authors recorded these data from weather stations “located 1-7 km” from the monitoring sites, which is of low accuracy to make these models reliable.

In general, both models are not well described. Furthermore, the model diagnostics section is confusing.

Results

L 178: “slight positive correlation with RH”; At least for this reviewer, a correlation value of R2= 0.04, is almost no correlation. However, authors in the figure text said: “A positive relationship between trap catch and increasing relative humidity is shown”, which is a bit confusing for the reader.

The mean of SWD trapped predicted in the GLMM (Table 1) does not fit well with the “true trap catch”, which is worrying. At 1549 DD, the GLM model predicts that there are 6.6 D. suzukii adults/trap but in reality, the data showed a twice flies captures (13.7 D. suzukii adults/trap). This data could make the GLMM not a consistent model to follow the SWD dynamics in cherry.

Discussion

Finally, other factors influencing SWD dynamics were mostly not detailed or discussed and final conclusions regarding how predictive models could support crop protection against D. suzukii were premature given the data presented.

Reviewer #2: PONE-D-19-35638

I appreciated the approach of this paper. It is well-written, though I had a few copy edit comments. The main issue is lack of independent, validating data and potential over-reach of the conclusions. The data are limited to a very specific crop system and the results should not be generalized to the landscape level. One of the major oversights is the lack of discussion about the potential impact of the insecticide applications on the number of adult flies trapped, even though the introduction stated that there could be five or more applications. Tart cherries often use rather strong chemistries such as dimethoate that could have a huge influence on the number of flies trapped. Also I would have liked to know if traps were on orchard borders or in interiors, as the spatial distribution of traps is known to influence captures. Finally, it would have been great to have some observations linked to the trap capture data. Most growers are giving up on traps, they are too cumbersome and time consuming. The most important variable is the infestation risk to the crop, not how many are caught in traps so that was perhaps a missed opportunity. It would be great to see if the model could predict first infestation, or total infestation on managed and/or untreated crop. That said, the data and analysis presented are relatively sound and meet the criteria for publication in PLOS. I recommend acceptance after minor changes are implemented. I had two uploaded documents: 1) marked up manuscript, and 2) line number comments corresponding to the marks on 1.

• Highlight, page 9

L28 prominent - common?

• Highlight, page 9

L31 with five or more applications under heavy pressure

• Highlight, page 9

L35 risk of developing resistance

• Highlight, page 10

L46 heat units

• Highlight, page 10

L50 to coincide with predictions of

• Strike Out, page 10

L53 the

• Highlight, page 10

L54 any reasons why phenology might be different in the midwestern US?

• Highlight, page 11

L69 would be nice to report GPS points for sites, latitude info could prove useful to others

• Highlight, page 11

L88 What resolution and time scale were the PRISM data?

• Highlight, page 11

L90 degree-days (DD) - what method used for DD?

• Highlight, page 13

L33 but wouldn't this be more in the SWD foraging environement rather than ambient? Were the orchards irrigated?

• Strike Out, page 14

L154 we?

• Highlight, page 16

L183 explanation for the confidence interval?

• Highlight, page 16

L186 explanation for CI missing

• Highlight, page 17

L206 smoothing protocol? Loess?

• Highlight, page 18

L244 but presumably if there was a later crop or host, the populations would likely increase well beyong the monitored period (Oct), or at least you don;t know from this data set, these data are specific to the tart cherry crop and should not be expanded to generalize the whole population

• Highlight, page 21

L297 Careful, no data on crop infestation are presented. What if damage preceded trap captures? Unhappy growers.

• Highlight, page 21

L309 Would be important to link the model to 1) crop susceptibility (color), 2) infestation/damage.

Reviewer #3: Degree day models to forecast the seasonal phenology of Drosophila suzukii

(Diptera: Drosophilidae) in Midwest climate (Kamiyama et al.)

The paper seeks to develop a general model for SWD in the Midwest by

fitting GLMM and GAMM statistical models to four years of field trap catch

data using degree days, RH, year, and site as independent variables. The

paper is well written and the statistical analyses well done.

The approach of putting field data on a dd scale is old (e.g., R.D. Hughes

and N. Gilbert @1968), and normalizing the data for each location and year

helps to put the phenology on a common scale based on the temperatures

experienced at the different sites and years (L 274-276). The first question

is what is the starting time for accumulating dd, and further how were the

dd calculated (the term non-linear time gives direction but not precise

information). Statistical models tend to be time and place specific

explaining why similar models from other locations do no work for the

Midwest (lines 252-265). In fact, the proposed model(s) may not work in

other areas of the Midwest. The parameter values should be given for the

models.

Mechanistic models have been developed that use biodemographic functions to

estimate the effects of physical factors (temperature, RH, photoperiod,

etc.) at short time steps on the dynamics of the target poikilotherm. In an

age -stage context, these models use abiotic and biotic factors as drivers

of the dynamics (doi:10.1016/j.ecolmodel.2016.05.014 and

doi:10.1007/s10530-016-1255-6). No model should be used to forecast

densities, hence the comment L 268-271 is inappropriate – at best one can

attempt to predict phenology “ for preemptive – IPM”. The authors recognize

this limitation L-308-309.

Some specific points:

L178- (t = 5.50, p < 0.001, are high relative to R2 = 0.04 – please check.

L201-203 This result is the critical result, and merits deeper explanation

of the conditional mode.

The work seeks to develop IPM relevant information, but fail to provide

accessible rules. Figures 1 and 2 were not particularly useful, showing a

very wide scatter of data interpreted statistically in the text.

The data reported in the supplemental materials is for 2018.

*** Note from Editorial Office: please note that the responses to the following questions are 'partly' but this is not an option in the reviewer form and 'No' has therefore been selected:

2. Has the statistical analysis been performed appropriately and rigorously? Partly

3. Have the authors made all data underlying the findings in their manuscript fully available? Partly -2018 ***

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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Submitted filename: PONE-D-19-35638_notes.pdf

Degree day models to forecast the seasonal phenology of Drosophila suzukii in tart cherry orchards in the Midwest U.S.

PONE-D-19-35638R1

Dear Dr. Guédot,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

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Antonio Biondi, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Dear authors,

Your manuscript has been reviewed by one of the referees that had reviewed the original version. Such reviewer found the manuscript not worthy of publication. However, after reading the new comments, the (very carefully)revised manuscript and the rebuttal letter, I totally disagree with such recommendation and, as a consequence, I am promoting the acceptance of this version for publication in PONE.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have fixed many of the comments that the reviewers had suggested to them. And the article has improved a lot, compared to the original version. However, at least for this reviewer, there are two key points that are important in interpreting this research, that is not fixed properly.

The authors have included an orchard with different cherry varieties in the study. Although they should be explained better the differences between these varieties (phenology, organoleptic, etc..). However, authors have justified by demonstrating that there is no difference between varieties of SWD catches during the study. At least for this reviewer, this could be justify 100% with statistics to show that there are no differences between cherry varieties on D. suzukii catch.

Finally, the second key point, is the most important of the article, because this manuscript is focused on the degree days models. At least for this reviewer, the weather stations are far from the fields where the traps were placed, and maybe this could be a reason to obtain strong confident models. However, this is a methodology mistake, that can't be fixed.

Other comments:

I also agree with the other reviewer about the insecticide treatments, which are necessary to consider to estimate the level of D. suzukii in relation to the treatments during the experiments.

Finally, no data on crop infestation are presented, which is crucial to know the damage on fruit in correlation with the DD models that authors did it.

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Reviewer #1: No